陆相湖盆页岩油储层形成演化过程与成因机制

Shale oil has great potential resources and are mainly enriched in continental strata in China. The continental shale oil reservoir has strong heterogeneity, and the study of reservoir is the basis and key of high efficiency development of continental shale oil and the weak link of current study for shale oil reservoir formation. This project focuses on the Shahejie Formation shale reservoir of Jiyang sub-basin, Lucaogou Formation shale reservoir of Jimsar Depression and Kongdian Formation shale of Cangdong Depression, using the multi-dimensional observation and quantitative test methods at different scales. We carry out the study of shale fabric characteristics and multi-scale heterogeneity characteristics, establishing the sediments origin and depositional process model, and the shale development model constraint by astronomical cycles, discussing the diversity of space-time distribution of shale. Based on the diagenesis and hydrocarbon generation simulation, analyze the evolution processes and products of organic and inorganic materials, clarify the organic-inorganic synergistic diagenesis mechanism combining of diagenetic fluid evolution and transport, and establish the shale diagenetic evolution models based on the multi component synergy. Analyze the storage pores origin, effectiveness, oil-bearing property and hydrocarbon occurrence of storage space on the basis of lithofacies during the diagenetic processes, discuss the splitting wet evolution process, and finally establish the shale oil reservoir formation mechanism and hydrocarbon enrichment model. Based on this project, we expect to publish more than 15 SCI periodicals of internationally famous magazines, create a high level shale oil research team.

我国页岩油资源潜力巨大，主要富集于陆相地层。陆相页岩油储层具有强的非均质性，储层研究是陆相页岩油高效开发的基础和关键，也是当前研究的薄弱环节。本项目以济阳坳陷古近系沙河街组、吉木萨尔凹陷二叠系芦草沟组及沧东凹陷孔店组页岩储层为对象，利用多维度不同尺度的观察及定量测试手段，开展页岩组构赋存与多尺度非均质性特征研究，理清细粒物质来源及沉积作用，在此基础上建立天文旋回约束的页岩发育模式，探讨页岩多尺度时空分布差异性成因；结合成岩模拟和生烃模拟，分析有机、无机组分成岩演化及产物，在物理模拟和数值模拟基础上，结合流体演化和物质传输，理清页岩有机-无机协同成岩作用机制，最终建立基于多组分协同作用的页岩成岩演化过程与模式；分析成岩过程中不同储集空间的成因、有效性、含油性及油赋存状态，厘定岩石组分润湿性特征及演化过程，弄清组构赋存、成岩流体与润湿性演化关系；建立基于有机质演化、成岩作用、储集空间形成、润湿性演化与页岩油赋存相互匹配的页岩油成储机制与烃类富集模式。通过本项目研究，以期取得页岩沉积作用和页岩油成储机制创新性成果，发表15篇以上国际知名杂志SCI期刊论文，造就一支高水平陆相页岩油研究团队。

陆相页岩组构复杂、非均质性强，沉积过程及成因机理研究难度大，页岩油储层形成是集有机质生烃与储集空间演化于一体的综合过程，更是当前研究的薄弱环节。本项目以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组、鄂尔多斯盆地三叠系延长组及济阳坳陷东营凹陷古近系沙河街组细粒沉积岩为研究对象，利用多尺度的观察及定量测试手段，明确了东西部陆相湖盆细粒沉积岩沉积特征及其差异性，揭示了不同时间尺度古环境周期性演化约束下的细粒沉积岩沉积过程与成因机理，阐明了细粒沉积岩有机-无机协同成岩作用机制，建立了富有机质页岩中烃类的富集模式。西部富火山物质页岩由盆外火山碎屑和陆源碎屑以及盆内碳酸盐等多物源供给混合沉积形成，东部贫火山物质页岩则由盆外陆源碎屑和盆内碳酸盐等物源供给混合沉积形成；底流搬运沉积物沉积的过程是鄂尔多斯盆地和吉木萨尔凹陷页岩发育的重要过程，湖平面升降及气候冷暖变化是控制纹层组合发育的关键，生物化学过程是济阳坳陷页岩发育的重要过程，盐跃层的周期性出现是控制纹层组合发育的关键。天文周期、太阳活动及季节更替在不同时间尺度上控制古气候的周期性变化，影响沉积物的输入及有机质的形成与保存，在陆相湖盆细粒沉积岩中形成了多尺度的沉积旋回，控制了有机质富集过程。页岩封闭系统内，不同组分纹层间的成岩相互作用与物质再分配是页岩油储层形成的关键，富火山物质页岩中含有大量过渡金属，在有机质热演化过程中起到催化生烃的作用，在有机质热成熟度较低条件下即可大规模生烃并在页岩内长石溶孔中富集；贫火山物质页岩中有机质热演化促进了方解石的重结晶作用，大量的晶间孔隙有利于烃类的运移、聚集和保存。